ENDOCRINEENDOCRINESYSTEMSYSTEM

ENDOCRINEENDOCRINESYSTEMSYSTEM

ENDOCRINE SYSTEMENDOCRINE SYSTEMENDOCRINE SYSTEMENDOCRINE SYSTEM

Regulates metabolic activities in Regulates metabolic activities in certain organs and tissues.certain organs and tissues.

It acts by secretion of hormones It acts by secretion of hormones which have slow and diffused which have slow and diffused effect.effect.

These hormones are secreted These hormones are secreted directly to the blood stream to directly to the blood stream to influence remote target organsinfluence remote target organs

Regulates metabolic activities in Regulates metabolic activities in certain organs and tissues.certain organs and tissues.

It acts by secretion of hormones It acts by secretion of hormones which have slow and diffused which have slow and diffused effect.effect.

These hormones are secreted These hormones are secreted directly to the blood stream to directly to the blood stream to influence remote target organsinfluence remote target organs

EndocrineSystem

DuctlessGlands

(thyroid)

DuctlessGlands

(thyroid)

Clustersof Cells(Islets)

Clustersof Cells(Islets)

EndocrineCells

(EE Cells)

EndocrineCells

(EE Cells)

STRUCTURESTRUCTURESTRUCTURESTRUCTUREConnective Tissue Stroma:Connective Tissue Stroma:

–Slender dense irregular collagenous Slender dense irregular collagenous connective tissue capsule, derived from connective tissue capsule, derived from the deep fascia of the neck.the deep fascia of the neck.

–Capsule sends septa which subdivide Capsule sends septa which subdivide the gland into lobules.the gland into lobules.

–Embedded within the capsule, on the Embedded within the capsule, on the posterior aspect, the parathyroid gland.posterior aspect, the parathyroid gland.

Connective Tissue Stroma:Connective Tissue Stroma:–Slender dense irregular collagenous Slender dense irregular collagenous

connective tissue capsule, derived from connective tissue capsule, derived from the deep fascia of the neck.the deep fascia of the neck.

–Capsule sends septa which subdivide Capsule sends septa which subdivide the gland into lobules.the gland into lobules.

–Embedded within the capsule, on the Embedded within the capsule, on the posterior aspect, the parathyroid gland.posterior aspect, the parathyroid gland.

PARENCHYMAPARENCHYMAPARENCHYMAPARENCHYMAComposed of thyroid follicles which are Composed of thyroid follicles which are formed of single layer of epithelial cells formed of single layer of epithelial cells encircling a spherical space containing encircling a spherical space containing homogenous colloid.homogenous colloid.The epithelial cells vary from low The epithelial cells vary from low cuboidal (in non active state) to cuboidal (in non active state) to columnar with microvilli (in active columnar with microvilli (in active state).state).The follicular cells are joined by tight The follicular cells are joined by tight junctions near the lumen and by gap junctions near the lumen and by gap junctions along the lateral membranes.junctions along the lateral membranes.

Composed of thyroid follicles which are Composed of thyroid follicles which are formed of single layer of epithelial cells formed of single layer of epithelial cells encircling a spherical space containing encircling a spherical space containing homogenous colloid.homogenous colloid.The epithelial cells vary from low The epithelial cells vary from low cuboidal (in non active state) to cuboidal (in non active state) to columnar with microvilli (in active columnar with microvilli (in active state).state).The follicular cells are joined by tight The follicular cells are joined by tight junctions near the lumen and by gap junctions near the lumen and by gap junctions along the lateral membranes.junctions along the lateral membranes.

The follicular cells have a rounded The follicular cells have a rounded nuclei, basophilic cytoplasm, distended nuclei, basophilic cytoplasm, distended RER, lysosomes, rod-shaped RER, lysosomes, rod-shaped mitochondria, supranuclear Golgi mitochondria, supranuclear Golgi complex and numerous short microvilli complex and numerous short microvilli extended into the colloid.extended into the colloid.

Basal lamina and reticular fibers Basal lamina and reticular fibers surround the epithelial follicular cells.surround the epithelial follicular cells.

Between follicles, there are network of Between follicles, there are network of blood vessels, unmyelinated blood vessels, unmyelinated sympathetic fiberssympathetic fibers

The follicular cells have a rounded The follicular cells have a rounded nuclei, basophilic cytoplasm, distended nuclei, basophilic cytoplasm, distended RER, lysosomes, rod-shaped RER, lysosomes, rod-shaped mitochondria, supranuclear Golgi mitochondria, supranuclear Golgi complex and numerous short microvilli complex and numerous short microvilli extended into the colloid.extended into the colloid.

Basal lamina and reticular fibers Basal lamina and reticular fibers surround the epithelial follicular cells.surround the epithelial follicular cells.

Between follicles, there are network of Between follicles, there are network of blood vessels, unmyelinated blood vessels, unmyelinated sympathetic fiberssympathetic fibers

Parafollicular cellsParafollicular cells– Small cells that produce calcitonin. They are Small cells that produce calcitonin. They are

enclosed within the basal lamina of the enclosed within the basal lamina of the follicular epithelium. They are not connected follicular epithelium. They are not connected to the follicular lumen.to the follicular lumen.

– They lie in clusters or single.They lie in clusters or single.

– They have rounded nuclei, moderate RER, They have rounded nuclei, moderate RER, elongated mitochondria, well-developed Golgi elongated mitochondria, well-developed Golgi complex and small dense secretory granules.complex and small dense secretory granules.

Parafollicular cellsParafollicular cells– Small cells that produce calcitonin. They are Small cells that produce calcitonin. They are

enclosed within the basal lamina of the enclosed within the basal lamina of the follicular epithelium. They are not connected follicular epithelium. They are not connected to the follicular lumen.to the follicular lumen.

– They lie in clusters or single.They lie in clusters or single.

– They have rounded nuclei, moderate RER, They have rounded nuclei, moderate RER, elongated mitochondria, well-developed Golgi elongated mitochondria, well-developed Golgi complex and small dense secretory granules.complex and small dense secretory granules.

Effects of T3 and T4Effects of T3 and T4Effects of T3 and T4Effects of T3 and T4Increase of the cellular metabolism.Increase of the cellular metabolism.

Increase growth rate in young.Increase growth rate in young.

Facilitate mental processes.Facilitate mental processes.

Stimulate other endocrine activities.Stimulate other endocrine activities.

Stimulate carbohydrate metabolism.Stimulate carbohydrate metabolism.

.................................................... etc..................................................... etc.

Increase of the cellular metabolism.Increase of the cellular metabolism.

Increase growth rate in young.Increase growth rate in young.

Facilitate mental processes.Facilitate mental processes.

Stimulate other endocrine activities.Stimulate other endocrine activities.

Stimulate carbohydrate metabolism.Stimulate carbohydrate metabolism.

.................................................... etc..................................................... etc.

Effects of CalcitoninEffects of CalcitoninEffects of CalcitoninEffects of Calcitonin

Inhibits bone resorption by Inhibits bone resorption by

osteoclasts, so lowering the osteoclasts, so lowering the

calcium concentration in blood.calcium concentration in blood.

Its release from the parafollicular Its release from the parafollicular

cells is stimulated by the high cells is stimulated by the high

calcium level of the circulating calcium level of the circulating

blood.blood.

Inhibits bone resorption by Inhibits bone resorption by

osteoclasts, so lowering the osteoclasts, so lowering the

calcium concentration in blood.calcium concentration in blood.

Its release from the parafollicular Its release from the parafollicular

cells is stimulated by the high cells is stimulated by the high

calcium level of the circulating calcium level of the circulating

blood.blood.

Hyperthyroidism (Graves’ disease)Hyperthyroidism (Graves’ disease)Hyperthyroidism (Graves’ disease)Hyperthyroidism (Graves’ disease)

Hyperplasia of follicular cells and increase of Hyperplasia of follicular cells and increase of the total size of the thyroid gland.the total size of the thyroid gland.

Increase production of thyroid hormones.Increase production of thyroid hormones.

It causes loss of weight, increase heart rate, It causes loss of weight, increase heart rate, hypertension, muscle tremors, tiredness, hypertension, muscle tremors, tiredness, nervousness, impotence in males and nervousness, impotence in males and excessive menstrual bleeding in females.excessive menstrual bleeding in females.

Hyperplasia of follicular cells and increase of Hyperplasia of follicular cells and increase of the total size of the thyroid gland.the total size of the thyroid gland.

Increase production of thyroid hormones.Increase production of thyroid hormones.

It causes loss of weight, increase heart rate, It causes loss of weight, increase heart rate, hypertension, muscle tremors, tiredness, hypertension, muscle tremors, tiredness, nervousness, impotence in males and nervousness, impotence in males and excessive menstrual bleeding in females.excessive menstrual bleeding in females.

GoitreGoitreGoitreGoitreInsufficient dietary intake of iodine will Insufficient dietary intake of iodine will cause thyroid gland to enlarge.cause thyroid gland to enlarge.

It is due to increase release of TSH from It is due to increase release of TSH from pituitary (as a response to low level of pituitary (as a response to low level of thyroid hormone of blood) which stimulate thyroid hormone of blood) which stimulate hypertrophy and proliferation of the hypertrophy and proliferation of the follicular cells.follicular cells.

Iodine intake will improve the condition.Iodine intake will improve the condition.

Insufficient dietary intake of iodine will Insufficient dietary intake of iodine will cause thyroid gland to enlarge.cause thyroid gland to enlarge.

It is due to increase release of TSH from It is due to increase release of TSH from pituitary (as a response to low level of pituitary (as a response to low level of thyroid hormone of blood) which stimulate thyroid hormone of blood) which stimulate hypertrophy and proliferation of the hypertrophy and proliferation of the follicular cells.follicular cells.

Iodine intake will improve the condition.Iodine intake will improve the condition.

HypothyroidismHypothyroidismHypothyroidismHypothyroidism

Fatigue, increase sleep, muscle weakness.Fatigue, increase sleep, muscle weakness.

Slow heart rate, decreased cardiac output and Slow heart rate, decreased cardiac output and blood volume, mental sluggishness.blood volume, mental sluggishness.

Constipation, increase body weight, loss of hair.Constipation, increase body weight, loss of hair.

Intolerance to cold weather.Intolerance to cold weather.

MyxedemaMyxedema: non-pitting edema.: non-pitting edema.

In congenital absence of thyroid it causes In congenital absence of thyroid it causes cretinismcretinism: failure of growth, mental retardation.: failure of growth, mental retardation.

Fatigue, increase sleep, muscle weakness.Fatigue, increase sleep, muscle weakness.

Slow heart rate, decreased cardiac output and Slow heart rate, decreased cardiac output and blood volume, mental sluggishness.blood volume, mental sluggishness.

Constipation, increase body weight, loss of hair.Constipation, increase body weight, loss of hair.

Intolerance to cold weather.Intolerance to cold weather.

MyxedemaMyxedema: non-pitting edema.: non-pitting edema.

In congenital absence of thyroid it causes In congenital absence of thyroid it causes cretinismcretinism: failure of growth, mental retardation.: failure of growth, mental retardation.

STRUCTURESTRUCTURESTRUCTURESTRUCTUREConnective Tissue Stroma:Connective Tissue Stroma:

– Thin collagenous connective tissue capsule.Thin collagenous connective tissue capsule.

– Capsule sends septa which subdivide the Capsule sends septa which subdivide the gland into incomplete lobules.gland into incomplete lobules.

– These septal trabeculae support the These septal trabeculae support the parenchymal cells and carries blood vessel, parenchymal cells and carries blood vessel, lymphatics and nerve fibers.lymphatics and nerve fibers.

– With age, the septa contain adipose cells.With age, the septa contain adipose cells.

Connective Tissue Stroma:Connective Tissue Stroma:– Thin collagenous connective tissue capsule.Thin collagenous connective tissue capsule.

– Capsule sends septa which subdivide the Capsule sends septa which subdivide the gland into incomplete lobules.gland into incomplete lobules.

– These septal trabeculae support the These septal trabeculae support the parenchymal cells and carries blood vessel, parenchymal cells and carries blood vessel, lymphatics and nerve fibers.lymphatics and nerve fibers.

– With age, the septa contain adipose cells.With age, the septa contain adipose cells.

STRUCTURESTRUCTURESTRUCTURESTRUCTUREParenchymal cells:Parenchymal cells:

–Are formed of branching and Are formed of branching and anastomosing cords or clusters of anastomosing cords or clusters of cells.cells.

–The parenchyma of the parathyroid The parenchyma of the parathyroid are formed of two types of cells: are formed of two types of cells: Chief (principal) cells and Oxyphil Chief (principal) cells and Oxyphil cells.cells.

Parenchymal cells:Parenchymal cells:–Are formed of branching and Are formed of branching and

anastomosing cords or clusters of anastomosing cords or clusters of cells.cells.

–The parenchyma of the parathyroid The parenchyma of the parathyroid are formed of two types of cells: are formed of two types of cells: Chief (principal) cells and Oxyphil Chief (principal) cells and Oxyphil cells.cells.

Chief CellsChief CellsChief CellsChief CellsThe major functional parenchymal cells.The major functional parenchymal cells.

Small in size (8 microns)Small in size (8 microns)

Slightly acidophilic cytoplasm containing Slightly acidophilic cytoplasm containing lipofuscin pigments and smaller dense lipofuscin pigments and smaller dense secretory granules containing the secretory granules containing the parathormone.parathormone.

It also contains RER, Golgi complex and It also contains RER, Golgi complex and elongated mitochondria.elongated mitochondria.

Some cells have also glycogen granules but Some cells have also glycogen granules but less parathormone granule (less active cells)less parathormone granule (less active cells)

The major functional parenchymal cells.The major functional parenchymal cells.

Small in size (8 microns)Small in size (8 microns)

Slightly acidophilic cytoplasm containing Slightly acidophilic cytoplasm containing lipofuscin pigments and smaller dense lipofuscin pigments and smaller dense secretory granules containing the secretory granules containing the parathormone.parathormone.

It also contains RER, Golgi complex and It also contains RER, Golgi complex and elongated mitochondria.elongated mitochondria.

Some cells have also glycogen granules but Some cells have also glycogen granules but less parathormone granule (less active cells)less parathormone granule (less active cells)

Oxyphil CellsOxyphil CellsOxyphil CellsOxyphil CellsLess in number.Less in number.

Larger than chief cells (more than 10 Larger than chief cells (more than 10 microns)microns)

Strongly acidophilic cytoplasm containing Strongly acidophilic cytoplasm containing less secretory granules, less RER and Golgi less secretory granules, less RER and Golgi complex and more mitochondria than the complex and more mitochondria than the chief cells.chief cells.

Appears in single form or in small groups.Appears in single form or in small groups.

It function is not known or it may be a stage It function is not known or it may be a stage of the chief cell development.of the chief cell development.

Less in number.Less in number.

Larger than chief cells (more than 10 Larger than chief cells (more than 10 microns)microns)

Strongly acidophilic cytoplasm containing Strongly acidophilic cytoplasm containing less secretory granules, less RER and Golgi less secretory granules, less RER and Golgi complex and more mitochondria than the complex and more mitochondria than the chief cells.chief cells.

Appears in single form or in small groups.Appears in single form or in small groups.

It function is not known or it may be a stage It function is not known or it may be a stage of the chief cell development.of the chief cell development.

Function of the Function of the parathyroidparathyroid

Function of the Function of the parathyroidparathyroid

The parathyroid hormone or the The parathyroid hormone or the (parathormone) increases the blood (parathormone) increases the blood level of calcium through:level of calcium through:

1.1. Activate osteoclasts to mobilize Activate osteoclasts to mobilize calcium from bone.calcium from bone.

2.2. Promote absorption of calcium from Promote absorption of calcium from the intestine.the intestine.

3.3. Increase reabsorption of calcium by Increase reabsorption of calcium by proximal convoluted tubules of proximal convoluted tubules of kidney.kidney.

The parathyroid hormone or the The parathyroid hormone or the (parathormone) increases the blood (parathormone) increases the blood level of calcium through:level of calcium through:

1.1. Activate osteoclasts to mobilize Activate osteoclasts to mobilize calcium from bone.calcium from bone.

2.2. Promote absorption of calcium from Promote absorption of calcium from the intestine.the intestine.

3.3. Increase reabsorption of calcium by Increase reabsorption of calcium by proximal convoluted tubules of proximal convoluted tubules of kidney.kidney.

Primary hyperparathyroidismPrimary hyperparathyroidismPrimary hyperparathyroidismPrimary hyperparathyroidism

Due to tumor in the chief cells and leads to Due to tumor in the chief cells and leads to high blood calcium level, low phosphate, high blood calcium level, low phosphate, heart disturbance and kidney stones.heart disturbance and kidney stones.

Treated by surgical removal of the Treated by surgical removal of the parathyroid tumor.parathyroid tumor.

Due to tumor in the chief cells and leads to Due to tumor in the chief cells and leads to high blood calcium level, low phosphate, high blood calcium level, low phosphate, heart disturbance and kidney stones.heart disturbance and kidney stones.

Treated by surgical removal of the Treated by surgical removal of the parathyroid tumor.parathyroid tumor.

Secondary hyperparathyroidismSecondary hyperparathyroidismSecondary hyperparathyroidismSecondary hyperparathyroidism

Occurs secondary to decrease absorption of Occurs secondary to decrease absorption of calcium from intestine due to Vit. D deficiency calcium from intestine due to Vit. D deficiency (in Rickets).(in Rickets).

So, the calcium level well be low in the blood.So, the calcium level well be low in the blood.

Occurs secondary to decrease absorption of Occurs secondary to decrease absorption of calcium from intestine due to Vit. D deficiency calcium from intestine due to Vit. D deficiency (in Rickets).(in Rickets).

So, the calcium level well be low in the blood.So, the calcium level well be low in the blood.

HypoparathyroidismHypoparathyroidismHypoparathyroidismHypoparathyroidism

Decrease parathormone (as after Decrease parathormone (as after

thyroidectomy) leads to lower thyroidectomy) leads to lower

blood calcium.blood calcium.

Leads to muscle cramps, tremors, Leads to muscle cramps, tremors,

mental confusion and memory mental confusion and memory

loss, may be fatal convulsions.loss, may be fatal convulsions.

Decrease parathormone (as after Decrease parathormone (as after

thyroidectomy) leads to lower thyroidectomy) leads to lower

blood calcium.blood calcium.

Leads to muscle cramps, tremors, Leads to muscle cramps, tremors,

mental confusion and memory mental confusion and memory

loss, may be fatal convulsions.loss, may be fatal convulsions.

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